Bifurcated Hydrogen Bonds in a Peptide Crystal Unveiled by X-ray Diffraction and Polarized Raman Spectroscopy
Bifurcated Hydrogen Bonds in a Peptide Crystal Unveiled by X-ray Diffraction and Polarized Raman Spectroscopy
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DOI：
10.1021/acs.cgd.3c00302
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发表时间：
2023-05-10
影响因子：
3.8
通讯作者：
Hayamizu, Yuhei
中科院分区：
文献类型：
--
作者：
Motai, Kazunori;Koishihara, Nao;Hayamizu, Yuhei
通过X射线结构分析和振动光谱研究了分子晶体中氢键的强度，发现氢键的原子间距与伸缩振动频率呈线性关系，但这些研究仅限于相对较小的分子化合物，如氨基酸。在这项研究中，我们使用四肽作为模型系统来研究多肽晶体中的氢键网络。单晶X-射线衍射仪分析表明，多晶结构中存在分叉氢键。拉曼光谱表明，酰胺键的振动频率与其原子间距离呈线性相关，但变化率明显低于前人的工作。碎片分子轨道计算还表明，分叉的氢键影响氢键的强度。本研究为探讨不同多肽晶体中的分叉氢键效应提供了一个有价值的模型体系。用偏振拉曼光谱表征了氢键的强度。发现随着氢键原子间距离的增加，酰胺键振动频率的变化率出乎意料地低。计算揭示了支化氢键对这一现象的贡献。
The strength of hydrogen bonds in molecular crystalshas been investigatedthrough X-ray structural analysis and vibrational spectroscopy, andthe interatomic distances and the stretching vibrational frequencyinvolving hydrogen bonds have been known to exhibit a linear relationship.However, these studies are limited to relatively small molecular compounds,such as amino acids. In this study, we employed tetrapeptide as amodel system to investigate the hydrogen bond network in the peptidecrystal. Single crystal X-ray diffraction revealed that the peptidecrystal structure had bifurcated hydrogen bonds. Raman spectroscopyexhibited that the vibrational frequency of amide bonds correlatedlinearly to their interatomic distance, but the rate of the changewas significantly low compared with previous works. Fragment molecularorbital calculations also revealed that bifurcated hydrogen bondsaffect the strength of the hydrogen bonds. This study provides a valuablemodel system for discussing the effects of bifurcated hydrogen bondsin various crystals of peptides.Thetetrapeptide crystal exhibited a hydrogen network extendingthrough the entire crystal. The strength of hydrogen bonds was characterizedby polarized Raman spectroscopy. An unexpectedly low rate of changein the vibrational frequency of the amide bond as increasing interatomicdistance of the hydrogen bond was found. A computational calculationrevealed the contribution of the branched hydrogen bonds to this phenomenon.